Malodors may be present in the environment from numerous sources both animate and inanimate. Many products and articles are available which aim to avoid or minimize the detection of such odors. In particular, it is particularly desirable to provide odor controlling materials to address the malodors which are generated by the human body, or from bodily fluids such as perspiration, urine, faeces, menstrual fluids, vaginal fluids and the like.
Articles like absorbent articles for example are designed to be worn by humans to absorb bodily fluids, such as urine, menstrual fluid and perspiration, etc. Examples of absorbent articles include sanitary napkins, pantiliners, disposable diapers, incontinence pads, tampons, perspiration pads, nursing pads and the like.
In use, the absorbent articles are known to acquire a variety of compounds, for example volatile fatty acids (e.g. isovaleric acid), ammonia, amines (e.g. triethylamine), sulphur containing compounds (e.g. mercaptans, sulphides), alcohols, ketones and aldehydes (e.g., furaldehyde) which release unpleasant odors. These compounds may be present in the bodily fluid or may be developed by chemical reactions and/or any fluid degradation mechanisms once the bodily fluid is absorbed into the absorbent article like for example a feminine pad. In addition bodily fluids usually contain micro-organisms and/or enzymes that can also generate malodorous by products as a result of degradation mechanisms like putrefactive degradation, acid degradation, proteins degradation, fat degradation and the like. Unpleasant odors, which emanate from absorbent pads when in use, may make the wearer feel self-conscious.
Various odor-controlling materials have been disclosed in the art to combat some of the unpleasant odors referred to above. Indeed solutions have been provided that use different technical approaches like masking, i.e., covering the odor with a perfume, or absorbing the odor already present in the bodily fluids and those generated after degradation.
Most of the focus in the prior art is found on the odor absorption technology. Examples of these types of compounds include activated carbons, clays, zeolites, silicates, starches, cyclodextrine, ion exchange resins and various mixture thereof as for example described in EP-A-348 978, EP-A-510 619, WO 91/12029, WO 91/11977, WO 89/02698, and/or WO 91/12030. All of these types of odor controlling agents are believed to control odor by mechanisms whereby the malodorous compounds and their precursors are physically absorbed by the agents and thus such agents hinder the exit of the odor from articles like absorbent articles. However, such mechanisms are not completely effective as the formation of the odor itself is not prevented and thus odor detection is not completely avoided.
Thus although these materials provide some control of odors associated with bodily fluids, there still exists a need of further improvement in terms of odor control over a wide range of malodorous compounds.
It is an object of the present invention to provide effective odor control over a wide range of malodors. More particularly, it is an object of the present invention to provide articles, especially disposable absorbent articles, which deliver outstanding odor control over a broad spectrum of malodors.
It has now been found that the above needs can be addressed by combining a cationic polysaccharide together with an odor-controlling agent, as the odor control system for an article, preferably a disposable absorbent article.
It has surprisingly been found that the combination of an odor controlling agent, typically an odor absorbent agent (e.g., zeolite and/or cyclodextrin) and/or a chelating agent (e.g., ethylene diamine tetracetate (EDTA)) together with a cationic polysaccharide, preferably chitosan material, in an article, like an absorbent article, typically coming into contact with bodily fluids, results in a synergistic effect in terms of odor control. Indeed this combination gives more odor reduction than the odor reduction associated with the use of one of these two classes of ingredients alone at the same total level (either said odor controlling agent alone or said cationic polysaccharide alone) in an absorbent article contacted with bodily fluids.
Actually the combination of a cationic polysaccharide with an odor-controlling agent in an article herein allows combining odor control mechanisms by which the overall malodor detection is synergistically reduced or even prevented.
Without to be bound by any theory it is believed that cationic polysaccharides, preferably chitosan materials, provide odor control of malodorous components associated with bodily fluid by multiple mechanisms.
Firstly, the odor absorption and retention characteristics of polysaccharides are due to the presence in the polymer structure of ionisable cationic functional groups. These groups are usually ammonium groups, a high proportion of which are in the salt form when the polymer is dry but which undergo dissociation and salvation upon contact with bodily fluid. In the dissociated state, the polymer chain will have a series of functional groups attached to it which groups have the same electric charge (e.g., —NH3+ +H3N—) and thus repel one another. This leads to expansion of the polymer structure, which, in turn permits further absorption of negatively charged odorous molecules and thus the control thereof.
Secondly, the positively charged cationic groups of the polysaccharides will interact with negatively charged anionic functionalities present in bodily fluids, like the carboxylic groups of proteins or hydroxylic acid bearing entities like short chain acid (e.g., butyric acid). This will result in the formation of tri-dimensional net between cationic polysaccharides and such molecules with anionic groups (gelification of the bodily fluids). This gelification will entrap most odorous molecules (like lipids, acids) thereby controlling malodor.
Thirdly and more importantly the cationic polysaccharides especially the aminopolysaccharides (chitosan materials) are believed to act as antimicrobial agents. Indeed the polysaccharides with their positively charged cationic groups will interfere with negatively charged surface of microorganism walls, thereby inhibiting the growth of such microorganisms or even killing such microorganisms. These cationic polysaccharides will also interfere with negatively charged surface of enzymes, thereby inactivating the enzymatic activity, which, like the microbial activity, are otherwise responsible for the formation of malodorous components. The cationic polysaccharides like chitosan materials further act by their indirect antimicrobial activity by linking some of the microorganism nutriments like lipids and/or minerals.
Surprisingly, the presence of the cationic polysaccharide, like chitosan material, increases the effectiveness of odor controlling agents like odor absorbent agents. Without to be bound by any theory it is speculated that the cationic polysaccharides herein, typically chitosan materials, control enzymatic and microbial growth and as a consequence the amount of malodorous compounds associated with the enzymatic and microbial activity occurring in bodily fluid. In other words, the cationic polysaccharides reduce or even prevent the formation of malodorous compounds, thereby reducing the total amount of malodor to be controlled. This allows the odor-controlling agent, typically the odor absorbent agent (e.g., zeolite and/or cyclodextrin) to work in reduced amount of active. Actually this results in a more effective as well as a sustained use of the odor-controlling agent herein. Indeed the saturation point of the odor absorbent agents when used in association with the cationic polysaccharides herein will be reached after prolonged periods of use, typically after prolonged wearing time of an absorbent article (pantiliner, pad) coming into contact with bodily fluid, as compared to when used alone in absence of the cationic polysaccharides in the same conditions.
Advantageously it is believed that the odor controlling agents, typically the odor absorbent agents, also help the cationic polysaccharides in reducing malodor by adsorbing not only odor present in the bodily fluids but also volatile odor present in the head space (space between the absorbent article and the urogenital surface). This combination is thus active too towards volatile malodor components, which escape from the bodily fluids and hence would not come in direct contact with the polysaccharides. Actually this combination allows odor control over a wider range of malodorous components, which would otherwise not have been fully controlled by one of these two classes of ingredients used alone.
Surprisingly the presence of a chelating agent on top of the cationic polysaccharide, namely chitosan material, results in increased antimicrobial properties. Without to be bound by any theory it is believed that the chelating agents used herein complete the antimicrobial properties of the cationic polysaccharides, by their indirect antimicrobial activity. Indeed the chelating agents have the ability to link some of the microorganisms nutriments like positively charged growth factors, typically Ca++, K+, Mg++. Advantageously the combination of these two preventing mechanisms results in a synergistic reduction in odor formation.
In a preferred embodiment herein the disposable absorbent articles have an apertured polymeric film topsheet. This topsheet contributes to further improve the odor control benefit.
In another preferred embodiment herein the disposable absorbent articles have a breathable backsheet. This contributes to a further improved odor control benefit. Even more preferred herein the disposable absorbent articles have both a breathable backsheet and an apertured polymeric film topsheet.
The present invention is preferably directed to disposable absorbent articles like pantiliners, feminine napkins, incontinent pads, diapers, tampons, interlabial pads, perspiration pads, surgical pads, breast pads, human or animal waste management devices and the like. Other articles suitable for use according to the present invention further include articles designed to be contacted with the body such as clothing, bandages, thermal pads, acne pads, cold pads, compresses, surgical pads/dressings and the like, body cleansing articles like impregnated wipes/tissues (e.g. baby wipes, wipes for feminine intimate hygiene), articles for absorbing perspiration such as shoe insoles, shirt inserts, and the like, and articles for animals like litters and the like.